Rod reduction device

ABSTRACT

A rod reduction device includes a housing defining a longitudinal axis. The housing has first and second arms extending distally therefrom. The distal ends of the arms are configured to releasably attach to a bone anchor. An anvil is operatively associated with the first and second arms of the housing and translatable along the longitudinal axis for facilitating the insertion of a spinal rod into the bone anchor. The anvil and each arm are positionable between an open position and a closed position.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 12/996,874, which was filed on Dec. 8, 2012, which is aNational Stage Entry of PCT/US2009/047002, which was filed Jun. 11,2009, now U.S. Pat. No. 8,308,729, and claims the benefit of U.S.Provisional Application No. 61/131,645, which was filed Jun. 11, 2008and U.S. Provisional Application No. 61/086,957, which was filed Aug. 7,2008, the entire contents of which are incorporated herein by reference.

BACKGROUND

1. Technical Field

The present disclosure relates to orthopedic surgery devices forstabilizing and fixing the bones and joints of the body. Particularly,the present disclosure relates to a manually operated device forreducing a spinal rod into a bone anchor in a controlled, measuredmanner.

2. Description of Related Art

The spinal column is a complex system of bones and connective tissuesthat provides support for the human body and protection for the spinalcord and nerves. The human spine is comprised of thirty-three vertebraeat birth and twenty-four as a mature adult. Between each pair ofvertebrae is an intervertebral disc, which maintains the space betweenadjacent vertebrae and acts as a cushion under compressive, bending androtational loads and motions.

There are various disorders, diseases and types of injury that thespinal column may experience in a lifetime. The problems may include butare not limited to scoliosis, kyphosis, excessive lordosis,spondylolisthesis, slipped or ruptured disc, degenerative disc disease,vertebral body fracture, and tumors. Persons suffering from any of theabove conditions typically experience extreme or debilitating pain andoften times diminished nerve function.

One of the more common solutions to any of the above mentionedconditions involves a surgical procedure known as spinal fusion. Aspinal fusion procedure involves fusing two or more vertebral bodies inorder to stabilize or eliminate motion at the intervertebral disc orjoint. To achieve this, natural or artificial bone, along with a spacingdevice, replaces either part, or all of the intervertebral disc to forma rigid column of bone, which is stabilized by mechanical hardware.

The mechanical hardware used to immobilize the spinal column typicallyinvolves a series of bone screws/anchors and metal rods or plates. Whenthe spine surgery is performed posteriorly, it is common practice toplace bone anchors into the vertebral bodies and then connect a metalrod between adjacent vertebral bodies. When the spine surgery isperformed anteriorly, it is common practice to attach a thin metal platedirectly to the vertebral bodies and secure it to each vertebral levelusing one or more bone screws.

The process of properly inserting the spinal rod into the receiving slotof a bone anchor and then securing that connecting rod in place canoften require that the surgeon use a number of instruments and expend agreat deal of time and effort. When bone anchors in several adjacentvertebrae are to be securely connected by a spinal rod, the repeatedprocess of inserting the rod into the heads of the bone anchors and thensecuring the rod in place for each respective bone anchor can bedifficult, tiresome and time consuming. Further, the alignment of therod as it connects to each of the sequential bone anchors may requireadjustment during the procedure and, therefore it is desirable that adevice and method be provided by which the rod can be reduced into thehead of each of the sequentially aligned bone anchors and, as necessary,easily adjusted so as to facilitate the process for the surgeon withminimal effort and loss of time.

SUMMARY

The present disclosure is directed to a rod reduction device including ahousing defining a longitudinal axis and having first and second armsextending distally therefrom. The housing includes a housing boreextending longitudinally therethrough. The housing bore is configured toreceive a driver for engaging a bone anchor. The rod reduction device isconfigured to engage the driver that advances the rod reduction deviceand the bone anchor into bone.

The first and second arms of the housing are positionable between afirst position and at least one second position. The arms are parallelto each other in at least one position. The distal ends of the arms areconfigured to releasably attach to the bone anchor. The distal ends ofthe arms include at least one grasping feature for engaging the boneanchor.

An anvil is operatively associated with the first and second arms of thehousing and is translatable along the longitudinal axis for facilitatingthe insertion of a spinal rod into the bone anchor. The anvil includesfirst and second bores for receiving the first and second arms of thehousing. The first and second bores are parallel to each other. Theanvil is positionable between a first position and at least one secondposition. The anvil is configured to position the arms to a parallelposition upon moving the anvil a predetermined distance distally fromthe housing. The anvil includes an anvil bore extending longitudinallytherethrough. The anvil bore is configured to receive the driver forengaging the bone anchor.

In one embodiment, the anvil includes an anvil post disposed at thedistal end thereof.

In one embodiment, the rod reduction device includes a reduction screwthat advances the anvil. In this embodiment, the reduction screwincludes an engaging spool disposed on the distal end thereof, whereinthe engaging spool is disposed in mechanical cooperation with an anvilhead. The anvil head is coupled to the engaging spool via at least oneinterconnecting pin. A thrust bearing is operatively associated with theengaging spool and the anvil head, the thrust bearing being disposedtherebetween. The anvil head has a contoured surface.

In another aspect of the present disclosure, a method for providingspinal support includes providing a rod reduction device having ahousing defining a longitudinal axis and having first and second armsextending distally therefrom, wherein distal ends of the arms areconfigured to releasably attach to a bone anchor; and an anviloperatively associated with the first and second arms of the housing andtranslatable along the longitudinal axis for facilitating the insertionof a spinal rod into the bone anchor; wherein the anvil and each arm arepositionable between a first position and at least one second position.The method further includes securing the rod reduction device to thebone anchor, placing the rod between the first and second arms of thehousing, reducing the rod into the bone anchor with the rod reductiondevice, and locking the rod to the bone anchor. The method also includesmounting the at least one bone anchor and the at least one rod to atleast one vertebral body.

In another aspect of the present disclosure, a method for providingspinal support includes providing a plurality of rod reduction devices,each rod reduction device including a housing defining a longitudinalaxis and having first and second arms extending distally therefrom,wherein distal ends of the arms are configured to releasably attach to abone anchor; and an anvil operatively associated with the first andsecond arms of the housing and translatable along the longitudinal axisfor facilitating the insertion of a rod into the bone anchor; whereinthe anvil and each arm are positionable between a first position and atleast one second position; providing a plurality of bone anchors. Themethod further includes securing each rod reduction device to a boneanchor of the plurality of bone anchors, placing the rod between thefirst and second arms of each rod reduction device, sequentiallyreducing portions of the rod into the plurality of bone anchor with therod reduction devices; and sequentially locking portions of the rod tothe plurality of bone anchors.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects and features of the present disclosure willbecome more apparent in light of the following detailed description whentaken in conjunction with the accompanying drawings in which:

FIG. 1A is a perspective view of one embodiment of a rod reductiondevice in accordance with the present disclosure;

FIG. 1B is a perspective view, with parts separated, of the rodreduction device of FIG. 1A;

FIG. 2A is a perspective view of one embodiment of a reduction screw inaccordance with the present disclosure;

FIG. 2B is a top view of the reduction screw of FIG. 2A;

FIG. 3A is a perspective view of another embodiment of a rod reductiondevice shown in a first position prior to engaging a bone anchorassembly;

FIG. 3B a perspective view of the rod reduction device and the boneanchor assembly of FIG. 3A, the rod reduction device shown in a secondposition engaged with the bone anchor assembly;

FIG. 4 is a perspective view of one embodiment of a driver positioned toengage the rod reduction device and the bone anchor assembly of FIGS.3A-3B;

FIG. 5 is perspective view of the reduction screw of FIGS. 2A-2Bengaging the rod reduction device and the bone anchor assembly of FIGS.3A-3B;

FIG. 6 is a perspective view of a locking instrument engaging theassembly shown in FIG. 5;

FIG. 7 is a perspective view of one embodiment of a rod reduction devicein combination with the reduction screw of FIGS. 2A-2B and the boneanchor of FIGS. 3A-6, illustrating a post with a hexalobular endattached to the distal side of an anvil of the rod reduction device;

FIG. 8 is a perspective view of a driving instrument assembled toanother embodiment of a rod reduction device and the bone anchor ofFIGS. 3A-7;

FIG. 9 is a perspective view of the rod reduction device of FIG. 8; and

FIG. 10 is a perspective view, with parts separated, of the rodreduction device of FIGS. 8-9.

DETAILED DESCRIPTION OF EMBODIMENTS

Particular embodiments of the present disclosure will be describedherein with reference to the accompanying drawings. As shown in thedrawings and as described throughout the following description, and asis traditional when referring to relative positioning on an object, theterm “proximal” refers to the end of the device that is closer to theuser and the term “distal” refers to the end of the device that isfarther from the user. In the following description, well-knownfunctions or constructions are not described in detail to avoidobscuring the present disclosure in unnecessary detail.

Referring now to the drawings, in which like reference numerals identifyidentical or substantially similar parts throughout the several views,FIG. 1A illustrates a rod reduction device 10. In accordance with thepresent disclosure, the rod reduction device 10 includes a housing 20having first and second arms 30, 40 extending distally therefrom and ananvil 50 operatively associated with the first and second arms 30, 40.

With continued reference to FIG. 1A, the housing 20 defines alongitudinal axis “L” and includes a proximal end 20 a and a distal end20 b. The proximal end 20 a includes a top surface 22, which may becontoured, and a longitudinal opening 21. The housing 20 includes ahousing bore 23 extending therethrough. The longitudinal opening 21 andthe housing bore 23 may be engaged by a plurality of instruments “I”(e.g., a reduction screw 600 {FIGS. 2A and 2B} described in furtherdetail hereinbelow). In addition, the housing 20 includes a first notch24 and a second notch (not shown) that is substantially similar to thefirst notch 24, but is defined within the opposing side of the housing20. The first notch 24 and the second notch are configured for receivingthe respective first and second arms 30, 40. First and second channels25, 27 are cut through the housing 20 transverse to the longitudinalaxis “L” on opposing sides of the housing 20 for receiving a first armpin 25 a and a second arm pin 27 a (FIG. 3A) respectively therethrough.The second arm pin 27 a is the same as the first arm pin 25 a and eachis configured to support respective first and second arms 30, 40relative to the housing 20. As such, the first and second arms 30, 40can pivot relative to the housing 20.

Referring now to FIGS. 1A-1B, the first arm 30 is positioned within thefirst notch 24 and the second arm 40 is positioned within the secondnotch. The first and second arms 30, 40 receive arm pins 25 a, 27 athrough pin holes 25 b, 27 b disposed at the proximal end of arms 30,40. The first and second arms 30, 40 are pivotally attached to thehousing 20, wherein the arms 30, 40 may pivot through a predefined anglewith respect to the housing 20. Accordingly, the arms 30, 40 are movableor repositionable throughout a plurality of positions including an openposition and a closed position. At the distal end of each arm 30, 40 isa grasping feature 32, 42, which may be a hook or a claw disposed inmirror image with the opposing grasping feature 32, 42. Each graspingfeature 32, 42 is configured to releasably attach to a complimentarymating feature on a bone anchor “B” (See FIGS. 3A-3B). Each arm 30, 40includes an inwardly facing cut portion 44 for enabling the anvil 50 toreadily translate therealong.

Referring again to FIGS. 1A-1B, the anvil 50 includes parallel first anda second arm bores 52, 54 for translating along the first and secondarms 30, 40 from the open position to the closed position and along thelongitudinal axis “L” for facilitating the insertion of a spinal rod “R”(See FIG. 5) into the bone anchor “B” (See FIGS. 3A-3B). The anvil 50includes a longitudinal opening 51 and an anvil bore 53 extendingtherethrough. The longitudinal opening 51 and the anvil bore 53 may beengaged by a plurality of instruments “I” (e.g., a reduction screw 600{FIGS. 2A and 2B} described in further detail hereinbelow). An arcuatechannel 55 is disposed along the distal end of the anvil 50 transverseto the longitudinal axis “L” for engaging a spinal rod “R” (See FIG. 5).In the open position, the arms 30, 40 are separated and the anvil 50 isdisposed proximal to the housing 20. When the anvil 50 moves distally,the arms 30, 40 pivot toward each other, become parallel, and arepositioned in the closed position. The transition of the anvil 50 andarms 30, 40 from open to closed positions occurs when the anvil 50 hastranslated distally from the housing 20 within the first quarter of thedistance along the arms 30, 40 down the longitudinal axis measured fromthe housing 20 to the distal ends of the arms 30, 40. In particular, therod reduction device 10 is considered to be “closed” when the arms 30,40 are parallel and the anvil 50 has translated approximately 25% awayfrom the housing 20. When the rod reduction device 10 is in its closedposition, the grasping features 32, 42, e.g. the hook or claw geometry,engage complimentary mating recesses “M” of the bone anchor “B,” (FIGS.3A-3B) removably attaching the rod reduction device 10 to the boneanchor “B.” When the rod reduction device 10 is removably attached tothe bone anchor “B”, the two pieces act as a single unit and may becollectively introduced into the anatomy.

As illustrated in FIGS. 3A-3B, another embodiment of a rod reductiondevice 100 is shown in the open position engaging the bone anchor “B.”Rod reduction device 100 is substantially similar to rod reductiondevice 10, but rod reduction device 100 includes first and secondoutwardly facing cut portions 102, 104 disposed on the proximal ends offirst and second arms 130, 140 so that the anvil 50 may translatetherealong from the open position (FIG. 3A) to the closed position (FIG.3B).

As shown in FIG. 4, a driver 700 with a driving end 710, e.g., ahexalobular end, may be passed through the housing bore 23 disposedlongitudinally through the housing 20 and through the anvil bore 53disposed longitudinally through the anvil 50. In addition to the drivingend 710, the driver 700 includes a sleeve 720 configured to engagehousing 20. When the sleeve 720 engages the housing 20, the driver 700can transmit torque to the rod reduction device 10 and the bone anchor“B.” In operation, the user may employ driver 700 to insert the boneanchor “B” into the bone and to reduce the spinal rod “R” into the inthe saddle “X” of the bone anchor “B.”

In one exemplary method of operation, the user positions the bone anchor“B” close to a bone and places the sleeve 720 over the proximal end 20 aof the housing 20. Moreover, the user passes driving end 710 through thehousing bore 23 and the anvil bore 53 until the driving end 710 engagesa shaft portion “S” of the bone anchor “B.” Then, a torsional force isapplied to the driver 700. Upon application of such torsional force, therod reduction device 10 rotates along with the bone anchor “B” toadvance the bone anchor “B” distally into the bone.

Once the bone anchor “B” is advanced to its desired position, the driver700 and/or driver tube 800 may be removed and the reduction screw 600(FIGS. 2A-2B) may be inserted through the housing bore 23 (FIG. 5) andthe anvil bore 53. As shown in FIGS. 2A-2B and 5, the reduction screw600 has a head 610 disposed on the proximal end thereof for driving thereduction screw 600, a threaded portion 620 on the distal end foradvancing the reduction screw 600 through the housing bore 23 and theanvil bore 53, and a shoulder 630 positioned distally of the threadedportion 620. From the illustration in FIG. 5, the spinal rod “R” mayalso be introduced between the two arms 130, 140 of the rod reductiondevice 100 and above the saddle “X” of the bone anchor “B”. The threadsof the reduction screw 600 engage threads on the inside of the housingbore 23 (see FIG. 1A) such that when a torsional force is applied to thereduction screw 600 a controlled and measurable incremental linearadvancement of the reduction screw 600 occurs. As the reduction screw600 is advanced, it passes through the anvil bore 53 until the shoulder630 engages on the anvil 50. At this point, shoulder 630 rests on theanvil 50 and the reduction screw 600 is ready to drive anvil 50. Furtherdistal advancement of the reduction screw 600 drives anvil 50 distallyalong the first and second arms 30, 40. Eventually, the arcuate channel55 of the anvil 50 engages spinal rod “R.” Once the arcuate channel 55engages spinal rod “R”, further distal advancement of reduction screw600 causes the anvil 50 to drive spinal rod “R” distally into the saddle“X” of the bone anchor “B”.

After the spinal rod “R” has been fully reduced, or seated in the saddle“X” of the bone anchor “B”, the driving tube 800, a locking instrument(FIG. 6) may be placed overtop the entire assembly. Squeezing the lever810 of the driving tube 800 causes it to engage the bone anchor “B” andpull up on a coupling “C” of the bone anchor “B” while pushing down onthe reduction screw 600 and spinal rod “R” thereby fully locking thespinal rod “R” into the bone anchor “B” without applying any force tothe patient. Releasing the lever 810 disengages the driving tube 800from the bone anchor “B” so the driving tube 800 may be removed. Thereduction screw 600 may then be unscrewed, the anvil 50 retracted andthe rod reduction device 10, 100 may be disassembled from the boneanchor “B.” The driving tube 800 may fully or partially lock the boneanchor “B” onto the spinal rod “R.” The spinal rod “R” may be partiallylocked (i.e., reducing the spinal rod “R” in the saddle “X” {the spinalrod “R” can move transverse to the longitudinal axis “L”}) or fullylocked (i.e., pulling the coupling “C” up to the saddle “X” after thespinal rod “R” is reduced) to the bone anchor “B” in order to facilitateadjustment of adjacent bone anchors “B” along the spinal rod “R.”Constructs having multiple bone anchors “B” along the spinal rod “R” arecontemplated. The driving tube 800 may be used to lock one or morespinal rods “R” after assembling one or more completed spinal rod “R”and bone anchor “B” constructs. After one or more spinal rods “R” arereduced into one or more bone anchors “B” and adjusted for properplacement, each spinal rod “R” and each bone anchor “B” can be fullylocked into place as described hereinabove. Accordingly, each spinal rod“R” and bone anchor “B” construct may be partially or fully locked(individually or collectively) using the driving tube 800 as describedhereinabove. Thus, the bone anchor “B” and spinal rod “R” constructs mayprovide permanent spinal support to the patient.

In another embodiment of the rod reduction device 200 (FIG. 7), theanvil 250 is configured with an anvil post 260 disposed on the distalend thereof. The anvil post 260 has a hexalobular distal end 262. Thisembodiment of the rod reduction device 200 allows the anvil 250 to bemoved distally to secure the arms 130, 140 to the bone anchor “B” whilethe hexalobular distal end 262 mates with the screw shank “S” of thebone anchor “B.” Then, a driving instrument “D”, such as that shown inFIG. 8, may be used to drive the screw shank “S” of the bone anchor “B”into bone from a proximal end of the driving instrument “D.” The drivinginstrument “D” includes a distal end configured to engage the housing 20and transmit torque to the rod reduction device 300 and to the boneanchor “B” attached to rod reduction device 300. In operation, the usermay implant bone anchor “B” into bone before or after reducing thespinal rod “R” into the bone anchor saddle “X.” In order to implant boneanchor “B,” the user first places the distal end of the drivinginstrument “D” over the housing 20 and then rotates the drivinginstrument “D” while advancing the driving instrument “D” distally.During rotation, the distal end of driving instrument “D” transmits thetorque to the rod reduction device 300 and the bone anchor “B.”Consequently, the bone anchor “B” is incrementally introduced into thebone.

Before or after implanting the bone anchor “B” into the bone, the usermay reduce spinal rod “R” into the bone anchor saddle “X”. To achievespinal rod reduction, the anvil post 260 of anvil 250 is retractedproximally and a spinal rod “R” is placed between the arms 130, 140 ofthe rod reduction device 200. The user then rotates the reduction screw600 about longitudinal axis “L,” thereby driving anvil post 260distally. While the anvil post 260 moves distally, the hexalobulardistal end 262 of the anvil post 260 urges the spine rod “R” distally,reducing the spinal rod “R” into the bone anchor “B.”

An alternative embodiment of the rod reduction device 300 (FIGS. 8, 9and 10) is substantially similar to the embodiments of the rod reductiondevices described above. However, rod reduction device 300 includes areduction screw 310 disposed in mechanical cooperation with the housing20 and an anvil 350. The reduction screw 310 has an engaging spool 320at a distal end thereof for cooperation with interconnecting pins 330 a,330 b and an anvil head 360. The engaging spool 320 is substantiallycylindrical with an annular channel 322 constructed about the center.The anvil 350 has an anvil bore 352 adapted to receive the reductionscrew 310 including the engaging spool 320, a thrust bearing 370, andthe anvil head 360. The engaging spool 320 and anvil head 360 areconfigured to interconnect, being partially separated by the thrustbearing 370 sandwiched between the underside of the anvil head 360 andthe distal end of the engaging spool 320. Furthermore, the engagingspool 320, the anvil head 360 and the anvil 350 are all interconnectedvia the interconnecting pins 330 a, 330 b.

As shown in FIG. 10, the anvil head 360 has a substantially cylindricalbody with a cavity 362 constructed partially therethrough beginning atthe proximal end for receiving the thrust bearing 370 and a portion ofthe engaging spool 320. In addition, the anvil head 360 has a contouredsurface 364 at the distal end. The contoured surface 364 has twoprotrusions 365, 366, both of which are symmetrically disposedtransverse to the longitudinal axis “L” and are configured in a spacedapart relation relative to the centerline of the anvil head 360. Aparabolic channel 367 is defined by the interior walls of the twoprotrusions 365, 366 and is constructed to engage a spinal rod “R.” Thiscontoured surface 364 may be substantially “v-shaped” for providingbetter contact with the spinal rod “R.” Furthermore, the anvil head 360can have notches 361 a, 361 b, disposed in the cylindrical wall forinterconnecting the engaging spool 320, the anvil head 360, and theanvil 350 via the two interlocking pins 330 a, 330 b. Further still, theanvil head 360 may be made from a hard material for limiting deformationand providing increased surface-to-surface contact with the spinal rod“R” (See FIG. 7).

In operation, the threads of the reduction screw 310 engage the threadson the inside of the housing bore 23 such that when a torsional force isapplied to the reduction screw 310 a controlled and measurableincremental linear advancement of the reduction screw 310 occurs. As thereduction screw 310 is advanced, the anvil head 360 connected theretotranslates with the anvil 350 until it contacts the spinal rod “R” whilesimultaneously manipulating the arms 330, 340 into the closed position.As the anvil head 360 approaches the spinal rod “R,” the parabolicchannel 367 defined on the distal surface of the anvil head 362, e.g.the v-shaped surface, contours the spinal rod “R.” The thrust bearing370 translates the torsional force into thrust force along thelongitudinal axis “L” and begins the advancement of the spinal rod “R.”Further advancement of the reduction screw 310 reduces the spinal rod“R” into the bone anchor saddle “X.” In this embodiment, the proximalsurface of the reduction screw 310 may recess below the top surface ofthe housing 20 about 0.020 inches. This additional translation enablesfurther compression of the anvil head 362 on the spinal rod “R.”

Alternatively, and in addition to, a driver tube 800 (FIG. 6) may beremovably attached to the housing 20 and a similar torsional force willadvance the rod reduction device and bone anchor “B” as a single unit.Any number of prior art handles may be attached to the driver 700 ordriver tube 800 in order to obtain the necessary mechanical advantage toaid in applying the torsional force. It is contemplated that othertechniques and/or instruments known in the art may be utilized toinstall the bone anchor.

In use, any of the embodiments of the rod reduction devices disclosed inthe present disclosure may be employed to reduce the spinal rod “R” inthe saddle “X” of the bone anchor “B.” This spinal rod reduction mayoccur before or after implanting the bone anchor “B” to a bone. Toinsert the bone anchor “B” into the bone, the user may utilize drivinginstrument “D” or any other suitable instrument.

The user may also reduce the spinal rod “R” with any disclosed rodreduction devices. Regardless of the specific embodiment used, thegrasping features 32, 42 of each arm (e.g., 30 and 40) should engage themating features “M” of the bone anchor “B.” Then, the user translatesthe anvil (e.g., 50 or 250) distally along the first and second arms(e.g., 30 and 40) until the arms reach the closed position, therebysecuring the rod reduction device to the bone anchor “B”. After orbefore attaching the rod reduction device to the bone anchor “B,” theuser places the spinal rod “R” between the first and second arms (e.g.,30 and 40). Once the first and second arms (e.g., 30 and 40) have beenplaced in the second position, further distal advancement of the anvil(e.g., 50) urges the spinal rod “R” into the saddle “X” of the boneanchor “R.” Optionally, the user may lock the spinal rod “R” to the boneanchor “B” with a set screw (not shown).

In another exemplary method of operation, the user may utilize multiplerod reduction devices (e.g, 100, 200, or 300) in a single surgery toreduce a single spinal rod “R” into multiple bone anchors “R.” Thisspinal rod reduction may occur before or after implanting the boneanchor “B” to a bone. In any event, during this operation, the usersequentially secures each rod reduction device to a bone anchor. Afteror before attaching the rod reduction devices to the bone anchors “B,”the user places the spinal rod “R” between the first and second arms(e.g., 30 and 40) of each rod reduction device. Then, the usersequentially manipulates each rod reduction device (as discussed above)to selectively reduce portions of the spinal rod “R” into each boneanchor “B.” At the end, the spinal rod “R” would be reduced into thesaddles “X” of each bone anchor “R.” After reducing the spinal rod “R”into the bone anchors “B,” the user may sequentially lock the spinal rod“R” to each bone anchor “B” with set screws (not shown)

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Therefore, the abovedescription should not be construed as limiting, but merely asexemplifications of presently disclosed embodiments. Thus the scope ofthe embodiments should be determined by the appended claims and theirlegal equivalents, rather than by the examples given.

What is claimed is:
 1. A rod reduction device, comprising: a housingdefining a longitudinal axis; a first arm and a second arm that extenddistally from the housing, each of the first arm and the second armincluding a proximal end and a distal end, the first arm pivotablysecured to the housing at a first location and the second arm pivotablysecured to the housing at a second location different from the firstlocation, the proximal ends of the first arm and the second arm beingpivotably secured to the housing such that the distal ends of the firstarm and the second arm are releasably attachable to a bone anchor uponbeing pivoted relative to the housing about the proximal ends of thefirst arm and the second arm, respectively, each of the first and secondarms including respective first and second outer surfaces; and an anvilsupported on the first arm and the second arm and being distallytranslatable relative to the housing along the first arm and the secondarm such that the anvil engages the first and second outer surfaces ofthe first and second arms to transition the first and second arms from anon-parallel orientation towards a parallel orientation and forfacilitating insertion of a spinal rod into the bone anchor, the anvildefining an arch that opens distally.
 2. The rod reduction device ofclaim 1, wherein the anvil extends around the first arm and the secondarm.
 3. The rod reduction device of claim 2, wherein the anvil defines afirst opening and a second opening that receive the first arm and thesecond arm so that the first opening encircles an outer surface of thefirst arm and the second opening encircles an outer surface of thesecond arm.
 4. The rod reduction device of claim 3, wherein the firstopening and the second opening are disposed in parallel with thelongitudinal axis of the housing and extend through the anvil from aproximal end of the anvil to a distal end of the anvil.
 5. The rodreduction device of claim 4, wherein the housing includes a housingopening that extends longitudinally through the housing and the anvilincludes an anvil opening that extends longitudinally through the anvil,the housing opening and the anvil opening being aligned with thelongitudinal axis defined by the housing.
 6. The rod reduction device ofclaim 1, wherein the anvil positions the first and second arms in theparallel orientation upon moving the anvil a predetermined distancedistally from the housing.
 7. The rod reduction device of claim 1,wherein each of the distal ends of the first and second arms includes atleast one grasping feature that engages the bone anchor.
 8. The rodreduction device of claim 1, wherein the rod reduction device isengageable with a driver that advances the rod reduction device and thebone anchor into bone.
 9. A rod reduction device, comprising: a housingdefining a longitudinal axis and having a first arm and a second armthat extend distally from the housing, a distal end of the first arm anda distal end of the second arm being movable to releasably attach to abone anchor; an anvil operatively associated with the first arm and thesecond arm of the housing, the anvil being movable along thelongitudinal axis to insert a spinal rod into the bone anchor, the anvilincluding an anvil body that surrounds a portion of the first arm and aportion of the second arm within the anvil body, the anvil body definingat least one opening dimensioned to receive at least one of the firstand second arms, the anvil defining an arch that opens distally; and anactuator coupled with the housing and the anvil such that rotation ofthe actuator in a first direction translates the anvil distally, theactuator and the housing being threadably coupled together.
 10. The rodreduction device of claim 9, wherein the arch is arranged to engage asurface of the spinal rod when the anvil body is distally advanced. 11.The rod reduction device of claim 9, wherein the at least one opening ofthe anvil body includes a first opening and a second opening, the firstopening dimensioned to receive and encircle the first arm, the secondopening dimensioned to receive and encircle the second arm.
 12. The rodreduction device of claim 9, wherein each of the first arm and thesecond arm further includes a proximal end, the proximal ends of thefirst arm and the second arm being pivotably secured to the housing suchthat the distal ends of the first arm and the second arm are releasablyattachable to the bone anchor upon being pivoted relative to the housingabout the proximal ends of the first arm and the second arm,respectively.
 13. The rod reduction device of claim 9, wherein the firstarm and the second arm are movable relative to each other between anon-parallel orientation and a parallel orientation as the anvil movesalong the first arm and the second arm.
 14. The rod reduction device ofclaim 13, wherein the anvil positions the arms in the parallelorientation upon moving the anvil a predetermined distance distally fromthe housing.
 15. The rod reduction device of claim 9, wherein each ofthe distal ends of the first and second arms includes at least onegrasping feature that engages the bone anchor.
 16. The rod reductiondevice of claim 9, wherein the rod reduction device is engageable with adriver that advances the rod reduction device and the bone anchor intobone.
 17. A rod reduction device, comprising: a housing defining alongitudinal axis; a first arm and a second arm that extend distallyfrom the housing, each of the first arm and the second arm including aproximal end and a distal end, the proximal ends of the first arm andthe second arm being pivotably secured to the housing such that thedistal ends of the first arm and the second arm are releasablyattachable to a bone anchor upon being pivoted relative to the housingabout the proximal ends of the first arm and the second arm,respectively; an anvil supported on the first arm and the second arm andbeing distally translatable relative to the housing along the first armand the second arm to facilitate insertion of a spinal rod into the boneanchor, the anvil defining a first bore and a second bore that receivethe first arm and the second arm so that the first bore encircles asurface of the first arm and the second bore encircles a surface of thesecond arm, the anvil defining an arch arranged to engage an outersurface of the spinal rod when the anvil is distally advanced relativeto the housing; and a reduction screw operably coupled with the housingand the anvil such that movement of the reduction screw along thelongitudinal axis results in corresponding movement of the anvil alongthe longitudinal axis.